Primary lung cancer is divided into three main types including small cell lung cancer, non-small cell lung cancer, and mesothelioma. Small cell lung cancer is also called “Oat Cell” lung cancer because the cancer cells are a distinctive oat shape. There are three types of non-small cell lung cancer which are grouped together based upon similar behavior patterns and response to treatment which is different from small cell lung cancer. The three types of non-small cell lung cancer are squamous cell carcinoma, adenocarcinoma and large cell carcinoma. Squamous cell cancer is the most common type of lung cancer. It develops from the cells that line the airways. Adenocarcinoma also develops from the cells that line the airways, but it develops from a particular type of cell that produces mucus (phlegm). In large cell lung cancer, the cells appear large and rounded when viewed under a microscope. Mesothelioma is a rare type of cancer which affects the covering of the lung, the pleura. It is often caused by exposure to asbestos.
Secondary lung cancer is cancer that has started somewhere else in the body (for example, the breast or bowel) and spread to the lungs. The choice of treatment depends on where the cancer began. For example, cancer that has spread from the breast should respond to breast cancer treatments and cancer that has spread from the bowel should respond to bowel cancer treatments. The stage of a cancer provides information regarding how far a cancer has spread. Staging is important because treatment of the cancer is often decided based upon its stage. Staging is different for non-small cell versus small cell cancers of the lung.
Non-small cell cancer is divided into four stages. Stage I is very localized cancer with no cancer in the lymph nodes. In stage II, cancer has spread to the lymph nodes at the top of the affected lung. In stage III, cancer has spread near to where the cancer started. This can be to the chest wall, the covering of the lung (pleura), the middle of the chest (mediastinum) or other lymph nodes. Stage IV cancer has spread to another part of the body.
Small cell lung cancers are divided into two groups. This is because small cell lung cancer often spreads quite early. Even if spreading of the cancer is not visible on scans, it is likely that some cancer cells will have broken away and traveled through the bloodstream or lymph system. Accordingly, it is often preferred to treat small cell lung cancers as if they have spread, whether or not any secondary cancer is seen.
The two stages of small cell lung cancers are limited disease, that is cancer that can only be seen in one lung and in nearby lymph nodes, and extensive disease, that is cancer that has spread outside the lung to the chest or to other parts of the body. Because surgery is not usually used to treat small cell cancer, except in very early cases, the staging is not as important as it is with some other types of cancer. Chemotherapy with or without radiotherapy is usually preferred for treatment of small cell lung cancers. Initial scans and tests are used for comparison with later scans and test to see how well a patient is responding to treatment.
Procedures used for detecting, diagnosing, monitoring, staging and prognosticating lung cancer are of critical importance to the outcome of the patient. For example, patients diagnosed with early lung cancer generally have a much greater five-year survival rate as compared to the survival rate for patients diagnosed with distant metastasized lung cancer. New diagnostic methods which are more sensitive and specific for detecting early lung cancer are clearly needed.
Lung cancer patients are also closely monitored following initial therapy and during adjuvant therapy to determine response to therapy and to detect persistent or recurrent disease of metastasis. There is clearly a need for a lung cancer marker which is more sensitive and specific in detecting lung cancer recurrence.
Another important step in managing lung cancer is determination of the stage of the disease. Stage determination has potential prognostic value and provides criteria for designing optimal therapy. Generally, pathological staging of lung cancer is preferable over clinical staging because the former gives a more accurate prognosis. However, clinical staging would be preferred were it at least as accurate as pathological staging because it does not depend on an invasive procedure to obtain tissue for pathological evaluation. Staging of lung cancer would be improved by detecting new markers in cells, tissues or bodily fluids which could differentiate between different stages of invasion.
In the present invention, methods are provided for detecting, diagnosing, monitoring, staging and prognosticating lung cancer via six (6) Lung Specific Genes (LSGs). The six LSGs refer, among other things, to native proteins expressed by the genes comprising the polynucleotide sequences of any of SEQ ID NO: 1, 2, 3, 4, 5 or 6. In the alternative, what is meant by the six LSGs as used herein, means the native mRNAs encoded by the genes comprising any of the polynucleotide sequences of SEQ ID NO: 1, 2, 3, 4, 5 or 6 or levels of the genes comprising any of the polynucleotide sequences of SEQ ID NO: 1, 2, 3, 4, 5 or 6.
Other objects, features, advantages and aspects of the present invention will become apparent to those of skill in the art from the following description. It should be understood, however, that the following description and the specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only. Various changes and modifications within the spirit and scope of the disclosed invention will become readily apparent to those skilled in the art from reading the following description and from reading the other parts of the present disclosure.